This invention relates in general to an underwater lamp and more particularly to a gas operated underwater lamp that can be used for underwater illumination of a swimming pool.
There are known in the prior art a variety of underwater lamps that could be used for lighting swimming pools below the water line. There are electrically operable swimming pool lamps such as is exemplified by my prior U.S. Pat. No. 3,456,103 and by U.S. Pat. No. 3,192,379 issued to R. G. M. DeGarmo.
While for the most part such electrically operated underwater lamps can provide suitable underwater illumination for swimming pools, they do present, by reason of their electrical operation, a certain electrical shock hazard. Such hazard can be regarded as more potential than actual as where a failure occurs somewhere in the insulation of the electrical supply.
Gas operated underwater lamps have been known in the prior art, as is exemplified by U.S. Pat. No. 3,267,277 issued to M. R. McLamb. While a gas lamp does not present an electrical shock hazard, the major problem associated with gas lamps is that water vapor, which is one of the products of combustion, condenses inside the water submerged enclosure. This condensation not only fogs the lens of the lamp, but it also collects in the bottom of the enclosure and ultimately extinguishes the gas lamp.
The invention provides a gas operated underwater lamp in which any condensate formed does not accumulate but instead is re-vaporized and vented to the atmosphere.
Basically the invention provides a gas operated underwater lamp which comprises a watertight housing having a frontal opening, a translucent cover disposed across said opening and covering same, said cover being connected to the housing in watertight sealed relationship therewith, at least one gas burning incandescent mantle disposed within said housing, first conduit means extending into said housing and communicating with said mantle to supply gas thereto for burning thereby, second conduit means extending into said housing and communicating therewith to vent therefrom products of combustion resulting from the burning of said gas; said housing and cover having heat transfer surfaces which cooperate with said mantle to prevent accumulation within the housing of condensate from products of combustion, when said housing is submersed in a cooling liquid.
According to a preferred embodiment of the invention the lamp has a submersible watertight housing that contains two propane gas burning mantles as sources of illumination. The front of the housing has a translucent and preferably transparent cover lens which allows light from the incandescent mantles to project into the water of a swimming pool in which the housing of the lamp is submerged. A vent pipe is connected to the top of the housing and communicates with the interior thereof thereby allowing the products of combustion to exit the housing and be vented to the ambient atmosphere at the other end of the pipe. The vent pipe preferably has an inverted U-shaped configuration which allows one end of the pipe to support the housing below the water line in the pool while the other end of the pipe is located exterior to the pool and in a free space. Thus, the vent conduit adapts the lamp ideally for use in the common above-the-ground vinyl-lined pools. The lamp of the invention has two conduits, one the vent pipe, and another which communicates with each mantle to supply gas thereto. The gas supply conduit is expediently passed length-wise through the vent conduit which allows gas supply and venting to be effected through a single opening in the housing. For better direction and dispersion of light to the pool, a reflector is mounted behind each mantle within the housing.
To solve the condensation problem that impaired operation of prior art gas burning lamps, the heat transfer in the housing and cover lens is carefully controlled. The bottom and sides of the housing and the cover lens are made so as to have a relatively low co-efficient of heat transfer. This allows these elements to become warm enough to prevent condensation or dispel any condensation that forms when the mantles are first ignited. To prevent the interior of the housing, and consequently the exiting gases, from becoming excessively hot, the top of the housing is more thermally conductive and has a higher co-efficient of heat transfer as compared to the bottom and sides of the housing. Preferably the conductive top of the housing has interior and exterior cooling fins. The interior cooling fins are placed so as to carry any dripping condensate to an underlying pan supported within the housing and heated by the mantles. This causes such condensate as may be collected from the top of the housing to be vaporized and carried out the vent conduit by the cooled gases.
Ignition of the mantles is expediently effected by an igniter that is located under one of the mantles. Such igniter is conveniently of the battery operated spark type and lights directly an adjoining mantle whereupon the second mantle is lighted from the first after the gas is turned on. Such igniter poses no safety hazard in that it is used only for turning on initial operation and need not be electrically energized once the mantles have been lighted. For ease of operation, a switch is incorporated in the gas control valve so that ignition can be effected automatically when the gas to the mantles is turned on. The electrical wiring to the igniter is preferably passed through the vent conduit to avoid the need for any additional opening through the housing that must be sealed watertight.
It is, therefore, an object of the invention to provide a lamp suitable for underwater illumination of a swimming pool and which is operated by a gas fuel, such as propane. Another object of this invention is to provide an underwater lamp which can be conveniently used for illuminating the type of pools which are elevated above the ground. A further object of the invention is to provide a gas operated underwater lamp in which condensate from gas combustion is effectively removed from the lamp.
Other and further objects and advantages of the invention will become apparent from the following detailed description and accompanying drawings exemplifying a preferred embodiment of the invention.